In addition, other objects, desirable features and characteristics will become apparent from the subsequent summary and detailed description, and the appended claims, taken in conjunction with the accompanying drawings and this background.
In communication systems, data dedicated to specific users and system common data are usually transmitted on two different channels. However, for some communication applications, common data and dedicated data may be transmitted on the same channel.
In navigation systems such as a GNSS like (NAVSTAR-)GPS (Global Positioning System) or the future European GNSS GALILEO, or in indoor navigation systems, a large amount of common data (such as global system information) as well as transmitter-dedicated data (onboard generated data) is sent to diverse user systems.
For example, to this regard the L5 navigation message transmitted by GPS satellites is encoded according to a ½ convolutional scheme and comprises frames with each frame being divided into five sub-frames. In the first three sub-frames, satellite specific data such as the status and health and the ephemeris data of the transmitting satellite are contained, while the fourth and fifth sub-frames comprise common system data such as almanac data of the GPS satellites, the difference between the GPS and UTC time, and data on the ionosphere. Thus, a GPS user system receives identical data transmitted by all satellites of a GNSS, but it cannot really take advantage of the same data transmitted in parallel as the common and transmitter-dependent L5 navigation data are encoded within the same stream and spread through the unique signatures assigned to each GPS satellite.